Bilateral amastia in a female with X‐linked hypohidrotic ectodermal dysplasia

Abstract

Funding sources: no external funding. Conflicts of interest: none declared. Dear Editor, Ectodermal dysplasia is a clinically and genetically heterogeneous condition characterized by abnormal development of two or more of the following ectodermal‐derived structures: hair, teeth, nails and sweat glands. Anomalies in other organs including mammary glands (nipple and breast) may also be observed.1 Hypohidrotic or anhidrotic ectodermal dysplasia (HED/EDA), the most common phenotype of ED, is characterized by a triad of signs comprising sparse hair (hypotrichosis), abnormal or missing teeth (hypodontia or anodontia) and inability to sweat (hypo or anhidrosis). The most frequent form of HED/EDA is the X‐linked form (XLHED; MIM #305100) resulting from mutations in the EDA1 gene, located on chromosome Xq12–q13.1, which encodes the ectoderm signalling molecule ectodysplasin (MIM #300451), a member of the tumour necrosis factor (TNF) family; and mutations in the EDA receptor encoding gene EDAR, located on chromosome 2q11–q13 (MIM #604095), or in the EDAR‐associated death domain encoding gene EDARADD, located on chromosome 1q42–q43 (MIM #606603), have been shown to cause both autosomal recessive and dominant HED forms.2 These three forms are clinically indistinguishable, probably because they alter a single signal transduction pathway. This pathway is critical for initiation, formation and differentiation of skin appendages.3 4 5 We report the first case of a female patient with XLHED and bilateral amastia.